2
votes
0answers
19 views

Do the eggs for larger litters come from the same meiosis events, or different ones?

There are some species of animals that give birth to more than one pup at a time. In these species, are the fertilized eggs all from one or a limited group of meiosis processes, or are they from ...
0
votes
1answer
21 views

Chromatids in metaphase?

Please see the following picture: In my book, the author claims that these chromosomes are in metaphase (a metaphase stopped by cholchicin). I don't understand why they don't have two ...
4
votes
4answers
99 views

Collective name for the X- and Z-chromosomes

Chromosomes are grouped as sex chromosomes or autosomes, with the X, Y, Z and W all falling in to the former category. The Z and X are present both in the homogametic and heterogametic sexes, and the ...
0
votes
0answers
13 views

Does the Y chromosome carry structural information, or only switches + traceable ID?

The Y chormosome almost doesn't crossover with the X chromosome, and so the evolution of anything it encodes must be much slower, because by the Hill–Robertson effect beneficial mutations must occur ...
4
votes
1answer
45 views

X-inactivation in ovaries

Background In all eutherian (mammals excluding the marsupials), the female (who is $XX$ for the pair of sexual chromosomes) inactivates one of her $X$. This is called dosage compensation. This ...
2
votes
1answer
70 views

What does chromosome CHR_Un, CHR_MT in the ftp site of NCBI mean?

I am not a biologist. But need some genetic data. So I searched internet and reached NCBI's website. I came to know from the FAQ page that I can the complete genome data of organisms from ...
2
votes
0answers
26 views

examples of chromosomal aberrations with lack of sexual chromosomes?

Are there any examples in animals where individuals survive having no copies of their sexual chromosomes?
1
vote
1answer
42 views

How are new chromosomes replicated into the next generation via sexual reproduction?

If an individual has a new chromosome, which is very unlikely to happen, he will not have any luck in finding a sexual partner with this same trait. How will the offspring inherit this trait. And ...
3
votes
2answers
214 views

How was the Huntington's disease gene's location found?

I read in the book "Why we get sick." by Nesse and Williams that: Steady detective work and fabulous luck have enabled geneticists to pinpoint the Huntington's gene on the short arm of ...
1
vote
1answer
64 views

What does min mean?

I read that "trp operon is located at 27 min on E.coli chromosome." What does "min" mean ?
0
votes
0answers
34 views

Paracentric Inversion and Mutations Question Help Needed

Would someone please be able to help with questons 3 or 4. (one of the at least please) please don't report his as off-topic. first, this is NOT a homeowork question. It's a practice question I am ...
3
votes
1answer
441 views

Examples of animals with different number of chromosomes that can interbreed?

When I was first started to write this question, I wanted to know how species evolve to have a different chromosomal arrangement, such as having two pairs of chromosomes instead of one? However, I ...
7
votes
1answer
57 views

Are recessive, deleterious alleles less common on the X chromosome than the autosomes in humans?

As there is a potential for them to be more readily purged in hemizygous males (and in cell lineages in females with the deleterious-allele-bearing chromosome activated), I would expect the frequency ...
2
votes
2answers
60 views

Maintaining purebred pedigrees and how to lessen chance of getting disease?

Many breeds of dogs are known for a high incidence of genetic disorders. German shepherd and Saint Bernard dogs are predisposed to developing a crippling condition called hip dysplasia. Q: What ...
1
vote
0answers
30 views

Referencing the homologous chromosomes

There exist a co-ordinate system from chromosomes like "12p11.3". In this system, first integer range from 1 to 23 i.e it takes homologous chromosomes as a pair. If we want to distinguish among ...
3
votes
2answers
120 views

Question about Autosomal Recessive Alleles

I had a homework question that I could not figure out. It states: A woman has cystic fibrosis in her family and did not want to have a child that suffered from the disease. She and her spouse ...
3
votes
1answer
80 views

Why is Turner syndrome rarer than Klinefelter syndrome?

Turner syndrome occurs in 1-1000 to 1-5000 females, and Klinefelter syndrome occurs in 1-500 to 1-1000 males. Why is Turner so rare even though they both are caused basically by the same mechanism?
2
votes
1answer
46 views

Determining whether X chromosome from sperm or egg

Is there any way of determining which X chromosome a female inherited from her father and which from her mom ?
2
votes
1answer
132 views

recombination frequency problem

Three loci C, D and E are located on the same chromosome in this order. We found that the frequency of recombinants between C and D is 10% and that between D and E it is 20%. Assuming that ...
1
vote
0answers
39 views

How is the number of histones being related to the number of chromosomes [closed]

Please name me at least one reason. I am referring to rats and to humans, as well.
3
votes
1answer
119 views

What is the most genetically simple organism except viruses?

What is the most genetically simple organism (except viruses) on this planet? By simple I mean the least number of genes.
1
vote
2answers
171 views

what is knob heterochromatin?

I am reading a paper which discusses Maize Genome Structure. Descriptions of the structure is given in the papers introduction. I know about heterochromatin "heterochromatin stains intensely, ...
2
votes
1answer
106 views

What's the difference between a free chromosome fragment and an extrachromosomal array?

This is reference to a review on C. elegans mosaic analysis by Yochem and Herman, in which the authors make a distinction between free chromosome fragments and extrachromosomal arrays. For the ...
6
votes
4answers
424 views

Chromosomes are of different size but why do all chromosomes have similar GC percentage?

When I browsed NCBI I saw a pattern: even if the chromosome sizes, number of genes, and number of proteins are different, GC% in chromosomes tend to be similar. The examples are linked below. Yeast, ...
2
votes
2answers
112 views

Can a new Y-chromosome be created?

The major gene of the Y-chromosome is SRY. Would it be possible to get the X-chromosome and add SRY to create a "fuller" Y-chromosome? What advantage does the skinny Y-chromosome give an individual ...
4
votes
2answers
719 views

Chromosome 2 fusion?

I read this article by Jeffrey Tomkins and Jerry Bergman claiming to debunk chromosome 2 fusion. Is there anything wrong with these conclusions? " 1.The reputed fusion site is located in a ...
4
votes
1answer
139 views

How does a tiger have stripes?

A vague question, but let me try to explain. My friend explained to me that in females, some cells use one X chromosome, while all others use the other X chromosome. This can result in some ...
1
vote
1answer
196 views

Would two species of yeast with similar genome sizes have the same number of genes or chromosomes?

Similar organisms generally have similar genome sizes. Given this, would two species of yeast have the same number of genes and chromosomes? Edit: Fixed with thanks to @daniel-standage
2
votes
1answer
90 views

Have there been any experiments that duplicate chromosome copies from 23*2 to 23*3 or 23*4?

Deinococcus radiodurans is an amazing bacterium with a fantastic survival rate. It can survive to high doses of radiation, in a complete vacuum and in hydrochloric acid. How does this bacterium ...
3
votes
3answers
5k views

Evolutionarily speaking, why do humans have 46 chromosomes

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48. What caused humans to have 46? ...
4
votes
1answer
308 views

What phenotypes can arise from gender-related aneuploidy?

Humans normally have 46 chromosomes (two copies - one from each parent - of each of the 24 chromosomes: [1:22] + [XX or XY]). Aneuploidy is an abnormal number of chromosomes - Down's syndromes is an ...